Definition: [verb] seek to lessen the blame attaching to (a fault or offence); try to justify.
Example: he did nothing to hide or excuse Jacob's cruelty
Definition: [verb] release (someone) from a duty or requirement.
Example: it will not be possible to excuse you from attendance
Definition: [noun] a reason or explanation given to justify a fault or offence.
Example: there can be no excuse for any further delay
Definition: [noun] a poor or inadequate example of.
Example: that pathetic excuse for a man!